The present invention relates to the baking of semiconductor wafers and more particularly to apparatus for performing such a baking in a vapor sheath which both treats the wafer and removes heat from the environment.
While most baking treatments of semiconductor wafers are typically performed in batch furnaces or in large ovens through which the wafers are transported on belts, it has also been proposed to bake semi-conductor wafers by means of small local heaters which may be incorporated, on an in-line basis, in a continuous semiconductor fabrication line. For example, two different forms of hot plate constructions, for different purposes, are disclosed in copending, coassigned U.S. patent application Ser. Nos. 263,928 and 373,978. In each of these constructions, however, the process is, to some extent, open to the environment and, accordingly there is some unavoidable heat loss. As is understood by those skilled in the art, semiconductor fabrication is inherently a precision process and it is typically desired to carefully control all parameters affecting each of the various process steps. It is therefore highly undesireable to have a disruptive heat source located within the process area. It has also been found advantageous to perform certain reactive treatments of the wafers simultaneously with the baking and the prior art in-line systems do not facilitate such treatment.
Among the several objects of the present invention may be noted the provision of apparatus for performing in-line baking of semiconductor wafers; the provision of such apparatus which does not release unacceptable quantities of heat into the environment; the provision of such apparatus which sheathes the baking semiconductor wafer in the controlled vapor stream; the provision of such apparatus which performs reactive treatment of the wafers during baking by vapor supplied to the wafer surface; the provision of such apparatus which prevents release of reactive vapors into the environment; the provision of such apparatus which will treat wafers under precisely controllable and repeatable conditions; the provision of such apparatus which is not wasteful of reactive constituents; the provision of such apparatus which is highly reliable and is of relatively simple and inexpensive construction. Other objects and features will be in part apparent and in part pointed out hereinafter.